[Federal Register Volume 63, Number 141 (Thursday, July 23, 1998)]
[Rules and Regulations]
[Pages 39492-39496]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-19615]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-SW-22-AD; Amendment 39-10675; AD 98-15-26]
RIN 2120-AA64
Airworthiness Directives; McDonnell Douglas Helicopter Systems
Model 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N,
600N, and OH-6A Helicopters
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
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SUMMARY: This amendment supersedes an existing priority letter
Airworthiness Directive (AD) 98-03-15, applicable to McDonnell Douglas
Helicopter Systems (MDHS) Model 369, 369A, 369D, 369E, 369F, 369FF,
369H, 369HE, 369HM, 369HS, 500N, 600N, and OH-6 helicopters that
currently requires an inspection for main rotor blade (blade) cracks
and for missing or cracked adhesive or paint. This amendment requires
the same inspections required by the existing priority letter AD but
deletes the Model 369 (Army YOH-6A), specifies recording torque events
(TE),
[[Page 39493]]
and establishes a shorter retirement life for certain blades. This
amendment is prompted by an accident in which a blade failed on a Model
369D helicopter due to fatigue cracks. The actions specified by this AD
are intended to detect cracks that could lead to failure of the blade
and subsequent loss of control of the helicopter.
DATES: Effective August 3, 1998.
The incorporation by reference of certain publications listed in
the regulations was approved previously by the Director of the Federal
Register as of May 29, 1996 (61 FR 24220, May 14, 1996).
Comments for inclusion in the Rules Docket must be received on or
before September 21, 1998.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Office of the Regional Counsel, Southwest Region,
Attention: Rules Docket No. 98-SW-22-AD, 2601 Meacham Blvd., Room 663,
Fort Worth, Texas 76137.
The applicable service information may be obtained from McDonnell
Douglas Helicopter Systems, Technical Publications, Bldg. M615/GO48,
5000 E. McDowell Road, Mesa, Arizona 85215-9797, telephone 602-891-
6522. This information may be examined at the FAA, Office of the
Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663 For
Worth, Texas; or at the Office of the Federal Register, 800 North
Capitol Street, NW., suite 700, Washington, DC.
FOR FURTHER INFORMATION CONTACT:
Mr. John L. Cecil, Aerospace Engineer, FAA, Los Angeles Aircraft
Certification Office, 3960 Paramount Blvd., Lakewood, California 90712,
telephone (562) 627-5229, fax (562) 627-5210.
SUPPLEMENTARY INFORMATION: On January 29, 1998, the FAA issued Priority
Letter AD 98-03-15, applicable to Boeing MDHS Model 369, 369A, 369D,
369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, 600N, and OH-6
helicopters, which requires an inspection for blade cracks and for
missing or cracked adhesive or paint. That priority letter AD was
prompted by an accident in which a blade failed on a Boeing MDHS Model
369D helicopter due to cracks. The blade that failed had accumulated
over 2,300 hours time-in-service (TIS). Subsequent investigation
revealed cracks in two other blades on the same helicopter.
Additionally, an operator reported finding a blade crack as a result of
complying AD 98-01-13. The cracks had initiated in the lower doubler
and propagated in a chordwise direction through the blade skin and
spar. These fatigue cracks may have been caused by residual stresses
induced by nonconforming doublers used to construct the blade. A
fatigue crack in a blade creates an unsafe condition. That condition,
if not detected, could result in failure of the blade and subsequent
loss of control of the helicopter.
The FAA previously issued AD 95-03-13, effective March 21, 1995,
Docket No. 94-SW-05-AD; AD 96-10-09, effective May 29, 1996, Docket No.
96-SW-02-AD; Priority Letter AD 98-01-13, issued December 31, 1997,
Docket No. 97-SW-68-AD, and Priority Letter AD 98-03-15 issued January
29, 1998, Docket No. 98-SW-06-AD, all of which mandate inspections in
the same general area. Priority Letter Ad 98-03-15 superseded Priority
Letter AD 98-01-13. This AD supersedes Priority Letter AD 98-03-15.
This AD does not supersede AD 95-03-13 or AD 96-10-09.
Since the issuance of AD 98-03-15, the FAA has determined the need
for establishing and recording of torque events (TE) plus the lowering
of the limit lives of the main rotor blades. The FAA has reviewed
Boeing McDonnell Douglas Helicopter Systems Service Bulletin No.
SB369H-243R3, SB369E-088R3, SB500N-015R3, SB369D-195R3, SB369F-075R3,
SB600N-007R2, dated July 13, 1998 (SB). The SB describes procedures for
a visual inspection of certain main rotor blades using a 10X magnifying
glass. The inspections are intended to detect cracking of the lower
surface of each blade starting at the root fitting and the doubler at
the inboard end of the blade and to detect debonding between the blade
root end fitting and doubler if missing or cracked adhesive or paint is
observed. For all affected helicopters except the Model 600N, with
blades installed that have 600 or more hours TIS, the SB provides that
these inspections are to be accomplished prior to further flight, and
thereafter at intervals not to exceed 25 hours TIS. For Model 600N
helicopters, the SB provides, prior to further flight, removal of
affected blades due to higher blade stresses on this model as compared
to other affected models. Additionally, this SB introduces flight hour
factoring as a means of addressing certain low cycle fatigue by
providing an alternate retirement life for the affected blades based on
TE. The manufacturer has determined that this action would not affect
any Model 369 (Army YOH-6A) helicopters. There are no known Model 369
helicopters in the U.S. fleet. Further, there were only two Model 369
helicopters produced as prototype Army YOH-6A. Therefore, the Model 369
helicopter is deleted from the SB. The FAA has also reviewed McDonnell
Douglas Helicopter Systems Service Information Notice No. HN-239, DN-
188, EN-81, FN-67, NN-008, dated October 27, 1965, which describes
procedures for an inspection for debonding between the blade root end
fitting and doubler if missing or cracked adhesive or paint is
observed.
Since an unsafe condition has been identified that is likely to
exist or develop on other MDHS Model 369A, 369D, 369E, 369F, 369FF,
369H, 369HE, 369HM, 369HS, 500N, 600N, and OH-6A helicopters of the
same type design, this AD requires, before further flights, and
thereafter at intervals not to exceed 25 hours TIS, for affected blades
that have 600 or more hours TIS, a visual inspection for cracks in the
lower surface of the blade root fitting and doubler at the inboard end
of the blade and for missing or cracked adhesive or paint at the root
end-to-doubler bonding line. The inspections will be accomplished using
a 10X or higher magnifying glass. Blades will be removed from service
before or upon the accumulation of a specified number of TE or hours
TIS, whichever occurs first. Since this same unsafe condition is likely
to exist on MDHS Model 600N helicopters and develop at a faster rate
because of higher blade stresses, this AD requires removal of certain
main rotor blades prior to further flight and replacement with
airworthy blades.
The short compliance time involved is required because the
previously described critical unsafe condition can adversely affect the
controllability and structural integrity of the helicopter. Therefore,
inspecting for blade cracks and missing or cracked adhesive or paint,
removing certain MDHS Model 600N helicopter blades, and reducing the
service life for the blades are required prior to further flight, and
this Ad must be issued immediately.
Since issuance of Priority Letter 98-03-15, the FAA has evaluated
additional data and has determined that the reduction of the service
life of the affected blades is appropriate. The actions are required to
be accomplished in accordance with this AD and Service Information
Notice No. HN-239, DN-188, EN-81, FN-67, NN-008, dated October 27,
1995, described previously.
Since a situation exists that require the immediate adoption of
this regulation, it is found that notice and opportunity for prior
public comment hereon are impracticable and that good cause exists for
making this amendment effective in less than 30 days.
The FAA estimates that 1,030 helicopters of U.S. registry will be
affected by this AD, and it will take
[[Page 39494]]
approximately 0.5 hours per helicopter to determine whether an affected
blade is installed, 1 work hour per helicopter with an affected blade
for the initial inspection, and 2.5 hours to replace a blade at a rate
of $60 per work hour. Required parts will cost approximately $6200 per
blade. Based on these figures, the total cost impact of the proposed AD
on U.S. operators is estimated to be $3,799,980 to inspect the blades
for cracks and to replace 588 affected blades.
Comments Invited
Although this action is in the form of a final rule that involves
requirements affecting flight safety and, thus, was not preceded by
notice and an opportunity for public comment, comments are invited on
this rule. Interested persons are invited to comment on this rule by
submitting such written data, views, or arguments as they may desire.
Communications should identify the Rules Docket number and be submitted
in triplicate to the address specified under the caption ADDRESSES. All
communications received on or before the closing date for comments will
be considered, and this rule may be amended in light of the comments
received. Factual information that supports the commenter's ideas and
suggestions is extremely helpful in evaluating the effectiveness of the
AD action and determining whether additional rulemaking action would be
needed.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the rule that might
suggest a need to modify the rule. All comments submitted will be
available, both before and after the closing date for comments, in the
Rules Docket for examination by interested persons. A report that
summarizes each FAA-public contact concerned with the substance of this
AD will be filed in the Rules Docket.
Comments wishing the FAA to acknowledge receipt of their comments
submitted in response to this rule must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket No. 98-SW-22-AD.'' The postcard will be date stamped and
returned to the commenter.
The regulations adopted herein will not have substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government. Therefore, in
accordance with Executive Order 12612, it is determined that this final
rule does not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
The FAA has determined that this regulation is an emergency
regulation that must be issued immediately to correct an unsafe
condition in aircraft, and that it is not a ``significant regulatory
action'' under Executive Order 12866. It has been determined further
that this action involves an emergency regulation under DOT Regulatory
Policies and Procedures (44 FR 11034, February 26, 1979). If it is
determined that this regulation otherwise would be significant under
DOT Regulatory Policies and Procedures, a final regulatory evaluation
will be prepared and placed in the Rules Docket. A copy of it, if
filed, may be obtained from the Rules Docket at the location provided
under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air Transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration amends part 39 of
the Federal Aviation Regulations (14 CFR part 39) as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 3913 is amended by adding a new airworthiness directive
(AD) to read as follows:
AD 98-15-26 McDonnell Douglas Helicopter Systems: Amendment 39-
10675. Docket No. 98-SW-22-AD. Supersedes Priority Letter AD 98-08-
15, Docket No. 98-SW-06-AD.
Applicability: Model 369A, 369D, 369E, 369F, 369FF, 369H, 369HE,
369HM, 369HS, 500N, 600N, and OH-6A helicopters with main rotor
blades Part Number (P/N) 369A1100-507 with Serial Number (S/N) D139
through D203, D209 through D223; P/N 369D21100-517 with S/N H664,
H665, H667, H669, H671, H672, H674, H676, H679, H680, H683 through
H724, H726 through H999, J000 through J039, J041 through J055; or P/
N 369D21102-517 with S/N 1976 through 2100, 2106 through 2115,
installed, certificated in any category.
Note 1. This AD applies to each helicopter identified in the
preceding applicability provision, regardless of whether it has been
modified, altered, or repaired in the area subject to the
requirements of this AD. For helicopters that have been modified,
altered, or repaired so that the performance of the requirements of
this AD is affected, the owner/operator must use the authority
provided in paragraph (f) to request approval from the FAA. This
approval may address either no action, if the current configuration
eliminates the unsafe condition, or different actions necessary to
address the unsafe condition described in this AD. Such a request
should include an assessment of the effect of the changed
configuration on the unsafe condition addressed by this AD. In no
case does the presence of any modification, alternation, or repair
remove any helicopter from the applicability of this AD.
Compliance: Required as indicated, unless accomplished
previously.
(a) For Model 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM,
369HS, 500N, and OH-6A helicopters with any affected main rotor
blade (blade) that has 600 or more hours time-in-service (TIS), to
detect cracks that could lead to failure of the blade and subsequent
loss of control of the helicopter, before further flight and
thereafter at intervals not to exceed 25 hours TIS, accomplish the
following:
(1) With each blade lifted off the droop stop, using a 10X or
higher magnifying glass, visually inspect the blade for any
chordwise cracking starting at the root fitting edge on the blade
lower surface doubler and skin or cracks on the doubler adjacent to
the root end fitting (Figure 1). If any cracking is discovered,
remove the blade and replace it with an airworthy blade.
Note 2: Boeing McDonnell Douglas Helicopter Systems Service
Bulletin No. SB369H-243R3, SB369E-088R3, SB500N-015R3, SB369D-195R3,
SB369F-075R3, SB600N-007R2, dated July 13, 1998 (SB), pertains to
the subject of this AD.
(2) With each blade lifted off the droop stop, inspect the lower
surface for missing or cracked adhesive or paint at the root end
fitting-to-doubler bond line (Figure 1). If any missing or cracked
adhesive or paint is discovered, remove and inspect the blade in
accordance with paragraph 3E of Part II of the Accomplishment
Instructions in McDonnell Douglas Helicopter Systems Service
Information Notice No. HN-239, DN-188, EN-81, FN-67, NN-008, dated
October 27, 1995. If there is any disbonding in excess of the
allowable margins specified in paragraph 3E of Part II of the
service information notice, replace the blade with an airworthy
blade.
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(b) For the Model 600N helicopters, before further flight,
remove any affected blade from service and replace it with an
airworthy blade not listed in the applicability section of this AD.
Blades removed from the Model 600N helicopters are not eligible for
use on any rotorcraft.
Note 3: The recurring inspection requirements, contained in
paragraph (a) of this AD, DO NOT apply to the Model 600N
helicopters.
(c) Affected blades are to be removed from service on or before
reaching either of the applicable new life limits. The new life
limits are determined by hours TIS or number of torque events (TE).
A torque event is defined as the transition to a hover from forward
flight. For this definition of TE, forward flight is considered to
be flight at any airspeed after attaining translational lift.
(1) For blades that do not have TE logged, prior to further
flight, log the TE in the rotorcraft log or equivalent record as
follows:
(i) Log the number of TE, if known.
(ii) For noncargo hook operations, if the number of TE is
unknown, log 6 TE for each hour TIS.
(iii) For cargo hook (external load) operations, or for any
combination of noncargo hook operations and cargo hook (external
load) operations, if the number of TE is unknown, log 20 TE for each
hour TIS.
(2) Make any entry into the component record or equivalent
record to reflect new life limits for blade P/N's as follows:
(i) For P/N 369A1100-507, Models 369A, 369H, 369HE, 369HM,
369HS, and OH-6A, enter 1,750 hours TIS or 10,600 TE, whichever
occurs first.
(ii) For P/N 369D21100-517, Models 369D and 369E, enter 2,500
hours TIS or 15,000 TE, whichever occurs first.
(iii) For P/N 369D21102-517, Model 369F, 369FF, and 500N, enter
2,500 hours TIS or 15,000 TE, whichever occurs first.
(d) After compliance with paragraph (c) of this AD, during each
operation thereafter, maintain a count of TE performed and
additional hours TIS accumulated, and, at the end of each day's
operations, add those counts to the accumulated number of TE and
hours TIS on the rotorcraft log or equivalent record.
(e) The blades are no longer retired based upon only hours TIS.
This AD revises the Airworthiness Limitations Section of the
maintenance manual by establishing a new retirement life for certain
blade P/N's based on hours TIS or a number of TE, whichever occurs
first.
(f) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used if approved by the Manager, Los Angeles Aircraft Certification
Office, FAA. Operators shall submit their requests through an FAA
Principal Maintenance Inspector, who may concur or comment and then
send it to the Manager, Los Angeles Aircraft Certification Office.
Note 4: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Los Angeles Aircraft Certification Office.
(g) Special flight permits will not be issued.
(h) The inspection required by paragraph (a)(2) of this AD shall
be done in accordance with McDonnell Douglas Helicopter Systems
Service Information Notice No. HN-239, DN-188, EN-81, FN-67, NN-008,
dated October 27, 1995. This incorporation by reference was approved
previously by the Director of the Federal Register as of May 29,
1996 (61 FR 24220, May 14, 1996). Copies may obtained from McDonnell
Douglas Helicopter Systems, Commercial Technical Publications, Bldg.
M615/G048, 5000 E. McDowell Road, Mesa, Arizona 85215-9797,
telephone 602-891-3667, fax 602-891-6522. Copies may be examined at
the FAA, Office of the Regional Counsel, Southwest Region, 2601
Meachum Blvd., Room 663, Fort Worth, Texas, or at the Office of the
Federal Register, 800 North Capital Street NW., suite 700,
Washington, DC.
(i) This amendment becomes effective on August 3, 1998.
Issued in Fort Worth, Texas, on July 17, 1998.
Henry A. Armstrong,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 98-19615 Filed 7-22-98; 8:45 am]
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